This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. AMBER is a suite of programs and a force field for molecular mechanics-based simulation. It is designed primarily for proteins and nucleic acids, and is being extended for small molecules. It includes: energy minimization, dynamics, NMR restrained dynamics, and free energy and normal mode calculations, as well as a graphical model builder X-windows program called Leap. It is developed and maintained by the David Case group with collaborators at other sites and distributed worldwide by the Case group. The Research Resource for Biocomputing, Visualization and Informatics helps support the AMBER development effort by providing system management and programming/algorithmic advice related to the graphics and 3D modeling aspects of this project.